Built-in 5200mAh rechargeable battery, this charger support you charge iWatch, Airpod, phones or other USB device at the same time without Uneven current distribution. Intelligent Safety Protection - More safety Supports over-charged, over-discharged, over-voltage, over-current and short circuit protection. Compatible with Airpods/ Airpods 2, Apple Watch SERIES 4 (40mm & 44mm) and Apple Watch SERIES 3/2/1 (38mm & 42mm). Compact Size - You can put it into your pocket or backpack with ease.